1. Field of the Invention
The present invention relates to improvements in an electric source apparatus for an electric vehicle, and more particularly to an electric source apparatus which improves vehicular weight without reducing the safety of vehicle passengers.
2. Description of the Prior Art
It is well known that electric vehicles are provided with a plurality of unit batteries as a drive electric source. The unit batteries are connected with a drive motor which drives the vehicle, an emergency switch which is operated in accordance with an impact detected by an impact sensor, and a main switch which is operated by a driver to start the electric vehicle. Such an electric vehicle is disclosed, for example, in Japanese Utility Model Provisional Publication Nos. 61-202101 and 64-47501. An electric source apparatus of the first listed prior art, JP-A-61-202101, is provided with an emergency switch which operates to cut the connection between the electric source (unit batteries) and a drive motor in the event that an impact sensor detects an impact in a vehicle collision or the like. An electric source apparatus of the other prior art, JP-A-64-47501, identified above is provided with a short circuit protecting device which includes a relay switch for cutting the connection between the electric source (unit batteries) and a drive motor.
However, with the above-mentioned conventional structure of the electric source apparatus, when the electric source is cut from the drive motor by the turning-off of the emergency switch and the like, the terminal voltage of the electric source remain at a high voltage similar to that in an operating condition. Accordingly, it is necessary to provide sufficient insulations for the electric source and high voltage circuit in order to protect vehicle passengers from receiving an electric shock. This insulation increases the vehicle weight and decreases the available travel distance of the vehicle.